Motor Comparison

[floatyflyer]

Hi All,

I have a question about trying to "compare" electric motors. I'm looking at buying a Balsa Cub Kit (Link) from Sig/Alien Aircraft. The recommended motor is a Himax HC-2808-1160 (Link). If I want to fit a different motor, what are the important numbers to compare (besides dimensions)? For example, here's a comparison to a much cheaper Turnigy motor from Hobby King (Link):

	Himax HC-2808-1160	Turnigy D2826-1100KV
KV	1160	1100
Max Power	110W	265W
Max Current	15A	19A

I see that the KV ratings are similar, which I'm assuming is probably the most important, but the max power is significantly different. Are these motors comparable? Also, is there a good reason why I'd want to spend close to 4 times as much on the Himax motor as opposed to the Turnigy one?

Thanks in advance for helping me figure this out!

 

[quorneng]

The easiest way to find a comparable motor is to look at is weight (47g) and it kV (1160).
The power of a motor is almost directly proportional to its weight and the kV determines how fast it rotates for a given number of battery cells.
It helps if the new motor has the same mounting hole positions as it then becomes a simple swop.
It looks like the Turnigy L2210C-1200 would have a comparable in performance, is quite a bit cheaper and it does include a prop driver suitable for its 3mm shaft.
It will not have the stick mount. If that is an essential part of the kit then I am afraid you are likely stuck with the recommended motor.

 

[floatyflyer]

Thank you! That all makes sense I think.

It will not have the stick mount. If that is an essential part of the kit then I am afraid you are likely stuck with the recommended motor.

What do you mean by stick mount? I’m not sure if I’m familiar. I’ve only ever built FT planes before so have just used their motor mounts for all of my planes so far!

 

[quorneng]

If you look at the picture of the motor in the link you gave it shows the motor mounted on a square stick using a special mouting adapter.
If the Balsa Cub kit uses a conventional 4 screw 'bulkhead' mounting then you should be ok with the HK motor.

 

[floatyflyer]

Oh I see. Yeah the balsa kit has a normal mount so it should be good. Thanks for the help!

 

[Merv]

..... Are these motors comparable? Also, is there a good reason why I'd want to spend close to 4 times as much on the Himax motor as opposed to the Turnigy one?

The Turnigy motor is more than twice the size of the other motor. If it will fit inside the space, it will work. It’s heavier and will effect the CG of your plane, you will need to adjust your battery placement to compensate.

The watts and Kv are the most important things to compare. The Turnigy motor has more than twice the watts. You might be better off selecting a smaller motor, one say around 150 watts. It will also be lighter.

You also need to look at which side the shaft sticks out. Some come out on the stationary side and some come out on the rotating side.

 

[floatyflyer]

That makes sense. Thank you! Power and KV seem to be the two main things to compare. I believe the motor could be made to mount in either direction on the kit if need be but I also know that worst case scenario it’s possible to move the shaft so it comes out the opposite side of the motor!

 

[Merv]

... it’s possible to move the shaft so it comes out the opposite side of the motor!

Yes, I’ve changed the shaft of several motors. It’s a pain to do, I’d need a good reason to intentionally buy a motor that needs to be changed.

 

[floatyflyer]

Yeah ok good to know! I might as well buy it so it mounts the right way in the first place if that’s an option!

 

[quorneng]

Merv that Turnigy L2210C-1200 I linked to is a 150W motor.

 

[floatyflyer]

Merv that Turnigy L2210C-1200 I linked to is a 150W motor.

I think Merv was referring to the original Turnigy motor that I was considering, not the one you had suggested.